Emmanuel Bertrand

Dextranase immobilization on epoxy CIM® disk for the production of isomaltooligosaccharides from dextran

Endodextranase D8144 from Penicillium sp. (EC 3.2.1.2.) was immobilized on an epoxy-activated monolithic Convective Interaction Media (CIM(®)) disk in order to produce isomaltooligosaccharides (IMOS) from Dextran T40 in a continuous IMmobilized Enzymes Reactor (IMER). Enzymatic parameters and structure of IMOS were studied for free and immobilized enzymes. The immobilization efficiency of endodextranase D8144 was about 15.9% (w/w) and the real specific activity was close to 6.5 U mg enz(-1). The Km values (4.8 ± 0.2 g L(-1)) for free and immobilized enzymes were the same, showing the absence of diffusional limitation. Moreover, specific patterns of DPs (Degrees of Polymerization) distributions were observed during the enzymatic hydrolysis by HPAEC-PAD (High Pressure Anion Exchange Chromatography-Pulsed Amperometric Detection). Thus, sought-after sizes of IMOS (DPs 8-10) were generated all over the hydrolysis. Finally, the results showed the high stability of this IMER since a relative enzymatic activity about 78% was measured after 5400 volumes column.

First Generation Bioethanol

At the beginning of 2016, first generation bioethanol still contributes to the majority of the 25 billion of gallons’ bioethanol produced worldwide, with the United States and Brazil producing approximately 85 % of the global production predominantly based on corn and sugarcane, respectively. However, concerns over the long-term sustainability of first generation bioethanol, such as the impacts on land use, water resource, the potential contamination of soils with the distillation residues, and the competition for food and feed production is frequently highlighted. Current fuel ethanol research and development strives to minimize these negative externalities. The fundamental role that process design plays during the development of cost-effective technologies is evaluated through the modification of the major pathways in first generation ethanol synthesis. In this context, the central role that better performing enzymes and microorganisms play in the intensity and integration of the process, such as the typical example of simultaneous saccharification and fermentation from starchy material in first generation facilities is acknowledged. Compensating ethanol production costs by the integrated valorization of energy and by-products for feed and green chemistry in a typical biorefinery concept are striking outputs of the first generation ethanol real scale experiment. Finally, rather than a mistake, first generation bioethanol should be considered as the first step that made it possible to gain the necessary experience for the successful implementation of the future greener generations biofuels from the field to the tank, starting with second generation lignocellulosic that is now coming on the market. In this context, integrated biorefineries are a promising way to diversify the usable feedstocks, leading to reduced facilities size and optimized supply-chains, to valorize more efficiently bagasse’s from sugarcane and corn stover or even to exploit the potential of microalgae to capture the carbon dioxide that is produced during the fermentation steps. Major stakeholders in bioenergy production are taking advantage of the large-scale successful development of first generation bioethanol, using the most promising processing schemes for next generation facilities, although the industry is still facing uncertainties with respect to its economic viability and longevity.

Modelling the Maillard reaction during the cooking of a model cheese.

During processing and storage of industrial processed cheese, odorous compounds are formed. Some of them are potentially unwanted for the flavour of the product. To reduce the appearance of these compounds, a methodological approach was employed. It consists of: (i) the identification of the key compounds or precursors responsible for the off-flavour observed, (ii) the monitoring of these markers during the heat treatments applied to the cheese medium, (iii) the establishment of an observable reaction scheme adapted from a literature survey to the compounds identified in the heated cheese medium (iv) the multi-responses stoichiokinetic modelling of these reaction markers. Systematic two-dimensional gas chromatography time-of-flight mass spectrometry was used for the semi-quantitation of trace compounds. Precursors were quantitated by high-performance liquid chromatography. The experimental data obtained were fitted to the model with 14 elementary linked reactions forming a multi-response observable reaction scheme.

Current advances in gibberellic acid (GA3) production, patented technologies and potential applications

Main conclusionGibberellic acid is a plant growth hormone that promotes cell expansion and division. Studies have aimed at optimizing and reducing production costs, which could make its application economically viable for different cultivars.Gibberellins consist of a large family of plant growth hormones discovered in the 1930s, which are synthesized via the terpenes route from the geranylgeranyl diphosphate and feature a basic structure formed by an ent-gibberellane tetracyclic skeleton. Among them, only four have biological activity, including gibberellic acid (GA3), which acts as a natural plant growth regulator, especially for stem elongation, seed germination, and increased fruit size. It can be obtained from plants, fungi, and bacteria. There are also some reports about microalgae GA3 producers. Fungi, especially Gibberella fujikuroi, are preferred for GA3 production via submerged fermentation or solid-state fermentation. Many factors may affect its production, some of which are related to the control and scale-up of fermentation parameters. Different GA3 products are available on the market. They can be found in liquid or solid formulations containing only GA3 or a mixture of other biological active gibberellins, which can be applied on a wide variety of cultivars, including crops and fruits. However, the product’s cost still limits its large and continuous application. New low-cost and efficient GA3 production alternatives are surely welcome. This review deals with the latest scientific and technological advances on production, recovery, formulation, and applications of this important plant growth hormone.

High-frequency, high-intensity electromagnetic field effects on Saccharomyces cerevisiae conversion yields and growth rates in a reverberant environment

Studies of the effects of electromagnetic waves on Saccharomyces cerevisiae emphasize the need to develop instrumented experimental systems ensuring a characterization of the exposition level to enable unambiguous assessment of their potential effects on living organisms. A bioreactor constituted with two separate compartments has been designed. The main element (75% of total volume) supporting all measurement and control systems (temperature, pH, agitation, and aeration) is placed outside the exposure room whereas the secondary element is exposed to irradiation. Measurements of the medium dielectric properties allow the determination of the electromagnetic field at any point inside the irradiated part of the reactor and are consistent with numerical simulations. In these conditions, the growth rate of Saccharomyces cerevisiae and the ethanol yield in aerobic conditions are not significantly modified when submitted to an electromagnetic field of 900 and 2400u202fMHz with an average exposition of 6.11u202fV.m-1 and 3.44u202fV.m-1 respectively.

Economic and Environmental Aspects of Biofuels

Within the framework of sustainable development, a quadruple transition (demographic, food, energetic and environmental) is necessary. The integrated biomass valorization, including the production of biofuels via the biorefinery concept lies at the cross section of these global challenges. Biofuels production competes for water and land use with respect to feed and food production. Securing these resources in an uncertain geopolitical environment is a strategic issue for many countries. It also has favorable (climate change mitigation) and adverse implications (fertilizers consumption, local pollutions). Therefore, the topic leads to huge political and economic debates at national and international scales. The results obtained from the implementation of supportive strategies for the development of this “new” bioeconomy indicate, at least in the near future, mixed results in comparison to the objectives that have been set. This may be explained by windfall effects created on the international markets and underline two imperative needs. The development and improvement of environmental methods, such as life cycle assessment expanded to the scope of international trade and not restricted to the regional or national economies will be necessary in order to install ambitious and unambiguous agreements for policymaker’s in the future international conferences such as the ones on climate change.

The Maillard Reaction in Food: An Introduction

In modern societies, most of the food being consumed has been processed. This introduction to the Maillard Reaction in Food provides informations about the main reactions that are occurring during the backing and cooking of food products. The processing of food is promoting non-enzymatic browning reaction involving proteins and reducing sugars. The products formed during this reaction are key players in the development of taste, flavour and colour and affects the consumers preferences. Maillard reaction products (MRP) can have positive or adverse effects on health with respect to anti/pro-oxidant potential, immunogenicity, allergenicity and carcinogenicity. Therefore, one century after its discovery by Louis Camille Maillard, the reaction still harbours many challenges for the scientific community and for the food. The development of increasingly more sensitive analytical techniques, including multi-omics approaches, and big data analysis are promising for a more refined understanding of this reaction.